Chapter IV. Ammonia will be again enumerated as a stimulant--Potash as a

catalytic--and lastly, all the alkalies as diuretics.

The alkalies are useful in gout and rheumatism in diminishing the acidity both of the blood and of the secretions. It is often advantageous to apply an alkaline wash locally around an affected joint, in the fluids about which the morbid process seems especially to have fixed itself. If we may receive a certain theoretical explanation of these two kindred diseases, still more light will be thrown on the advantage attending the employment of alkaline restoratives. To this I shall recur when I consider the Catalytics which are used to counteract these same disorders, not, as here, by restoring a wanting material, but apparently by determining the process in a different direction, and thus checking it altogether.

The action of Catalytics is more obscure than that of Restoratives, but there is generally a broad line between them. The most difficult case is that of the medicines used in ague and other periodic diseases; of these, for certain reasons that I shall state, I have grouped Quina and tonics among Restoratives, placing Arsenic among Catalytic medicines.

It seems to me that Cinchona bears the same relation to Arsenic in the treatment of ague, as Alkalies to Colchicum in gout; the former, in each case, supplying a needful material, the latter neutralizing a morbid process.

Thus, when air has been rendered impure by breathing, we may render it again respirable by adding fresh oxygen; but still more certainly, by neutralizing the carbonic acid.

ORD. IV. TONICS.

Under this term I intend to include only the bitter principles of vegetables. The chief medicines of this order are as follow:

_Alkaloids and neutral principles._--Quina, Cinchonia, Bebeerine, Narcotine, Salicine, etc.

_Bitter drugs._--Cinchona, Quassia, Cusparia, Gentian, Calumba, Chiretta, Centaurium, Menyanthes, Rhubarb, Hops, Elm and Willow barks, Tansy, Wormwood, Chamomile, Cascarilla.

The power by virtue of which these medicines are enabled to act as Tonics, is due, in each case, to a vegetable alkaloid or neutral principle, having a bitter taste. All of those mentioned above, with the exception of Salicine, contain Nitrogen. The uses of Tonics are of a twofold nature. Firstly, they are of use in simple debility and in atonic dyspepsia. Here they give an appetite, increase the muscular strength and powers of digestion, and improve the general health. In the second place, they have all, more or less, a curative power in Ague and other periodic disorders, caused by Marsh miasm. Many explanations have been given of this curious and double action of vegetable bitters; and some erroneous theories have been assumed, and false analogies attempted, in the classification of these remedies. The subject is certainly a difficult one, and there are, at starting, several questions which require a distinct consideration and reply. Upon the answers given to them it must depend whether they should rightly be grouped with blood-medicines or with nerve-medicines; and, if the former, with Restoratives or with Catalytics.

Do these medicines act primarily in the blood, or on the nerves? Is their action of a permanent character? Are there any substances in the blood which resemble them? May they remain in the blood, or are they always excreted? If acting in the blood, are they wont to effect a cure by supplying to it a material wanting, or by counteracting in it a morbid process?

These questions require each a satisfactory reply, before it can be proved that I have done rightly in classing Tonics among Restorative medicines; for they coincide with the minor propositions in which I have defined the action of such remedial agents.

Quina may be taken as the type of the whole order. It is the most powerful; and the others all more or less resemble it. Perhaps Cusparia bark comes nearest to the Cinchona alkaloids in its anti-periodic action. It is worthy of remark, that some common bitters which owe their efficacy, not to alkaloids, but to neutral principles, as Quassia, Calumba, and Gentian, possess the least control over periodic affections.

There can be no doubt that these active principles are all absorbed, and pass into the blood. They may easily be dissolved out of the vegetable which contains them, if not by simple water, at all events by such an acid liquid as we find in the stomach. We possess positive proof of absorption in the case of Quina, which has been detected by Tiedemann and Gmelin in the blood of a patient to whom it was administered.

Having them now in the blood, we arrive at the first question. Do Quina and other vegetable Tonics act on the blood or on the nerves? This has been answered at once by many writers, as if it were a thing of great simplicity. But it does not seem to be so. Tonics, as we know, have the power of communicating health and strength in debility produced by various causes, and also of arresting the progress of intermittent fever. Do they effect these things by bettering the condition of the blood, and, from it, that of the system at large, or do they at once, and in the first place, influence the nervous system? This is an important question, and it has been variously answered.

Dr. Pereira, in his classification of medicines, ranks them among _Cinetics_ ([Greek: kineô], to move,) which are defined to be medicines exerting a power over the motor system of nerves, and through them on the muscles. But in a subsequent account of Quina, he states that its action is quite inexplicable, and that its use in Ague must be ranked with some other special and ill-understood actions, as that of Mercury in Syphilis, or of Arsenic in Lepra.

Dr. Neligan, (in his work _On Medicines,_) lays it down that Tonics act as stimulants when given to a healthy man. Dr. Pereira, on the contrary, states what is more consonant with general experience, _i.e._ that a moderate dose of a tonic has little or no effect on a man in perfect health. Dr. Neligan admits that their action is permanent, and produced slowly; he also declines any explanation of the action of Quina and others in Ague, calling them specifics.

Some other authors have been still more decided in classing Tonics with nerve-medicines. Dr. Guy, (in his edition of _Dr. Hooper's Physician's Vade Mecum_,) considers that Stimulants and Tonics should rightly be classed together, for that Stimulants act as Tonics to the weak, and Tonics as Stimulants to the strong.

It should be observed, that the irritant action on the stomach of a large dose of a bitter medicine appears to have been the chief foundation of this frequent opinion of the stimulant action of tonics. The irritable stomachs of nervous persons are more easily affected in this way. Some too are met with who bear Tonics worse than others, on account of an idiosyncrasy or peculiarity of constitution. But this irritation, and the headache and febrile symptoms which succeed to it, do not surely constitute the proper action of a tonic medicine, which is found to operate most favourably when given in too small a dose to produce any thing like a stimulant effect. Nor do I think it proved that any true stimulants are capable of communicating a permanent tone to the system, or to any part of it.

Dr. Ballard also, (in _Ballard and Garrod's Materia Medica_,) states that Tonics acts first upon the nerves, and through them on the muscular system. He opposes them to Sedatives, and ranks them with stimulants; quoting Strychnia as an example of a stimulant which gives tone to the muscular system. But, in the first place, this alkaloid is quite exceptional among stimulants; and further, the comparison with Tonics seems unnatural, inasmuch as the action of Strychnia is more or less immediate, not slow and permanent, and it evidently influences the spinal system of nerves in the first place.

The results of large doses of Quina, in producing determination of blood to the head, ringing in the ears, and vomiting, seem to me to mark its action as an irritant poison, and not to be characteristic of Tonic medicines. (_Vide_ p. 91.)

The action of Tonics has been more correctly defined by another able authority. "Tonics," says Dr. A. Billing, "are substances which neither immediately nor sensibly call forth actions, like stimulants, nor repress them, like sedatives, but give power to the nervous system to generate or secrete the nervous influence by which the whole frame is strengthened."

This definition I would accept in a modified sense, considering that no permanent alteration in the nervous system can be produced without a primary impression on the blood. Dr. Billing further considers, that the supposed stimulant action of Tonics in some cases should either be attributed to the operation of the disease, or of some other medicine administered along with them; and that though in large doses they may sometimes produce a quick pulse with headache, and in other instances depression with nausea, yet that these effects should be ascribed merely to their irritating action on the stomach.

On the whole, it seems to me that those authors who, in defining the action of Tonics, have commenced by saying that they act on the nervous system, have started with a mistaken notion; and I am more of the opinion of Dr. A. T. Thomson, who classes them as medicines which act on the muscular and sanguiferous systems.

I consider, then, that Quina is not in the first instance a Neurotic medicine; and for the following reasons. The action of other nerve-medicines is distinguished by the following signs. It is quick, and very rapidly follows the administration of a substance. It is transient, and does not endure. It requires no particular state, but takes place in health: thus Alcohol stimulates and intoxicates both healthy and sickly, and Digitalis would subdue a Hercules. Most Neurotics are capable of acting without entry into the blood at large; mere contact with the nerves, as when they are applied externally, being sufficient for their action on those nerves. Again, Neurotics are chiefly used in cases in which the nervous system is unusually excited or depressed, and are of no permanent efficacy in diseases depending on blood-disorder. The action of Hæmatics is of an opposite kind.

Now is the primary action of Tonics distinguished by the above signs? Are they quick and sudden in action? Is their effect transitory? Is it evidenced in health as well as in disease? Do they act on the superficial nerves, when applied to them? In each case the answer must be a negative. In all of these particulars the operation of vegetable bitters differs from that of Neurotics, and coincides with that of Hæmatic medicines.

It appears that their action on the nervous and muscular systems is secondary. They could hardly in either case effect any permanent improvement without first acting on the blood, if we may argue from known analogies. For Neurotics and Astringents, which operate directly on these two systems, are alike transitory in the results of their action.

Another demonstration is required, before the presumption thus established can approach to a certainty.

We require proof to show that the disorders in which Tonics are used are blood-diseases. This does not seem to be difficult.

The condition of Debility, whatever its proximate cause, seems always to be traceable in the first place to a want in the blood, which interferes with the due exercise of their functions by the nerves and other organs, by impairing their nutrition. It follows fevers, and accompanies chronic diseases, in both of which cases the blood has been exhausted by continual waste and excretion, without the maintenance of a proper supply. In cancerous, scrofulous, scorbutic, and dyspeptic habits, the blood may be deteriorated by a fault in the assimilative processes. When in these instances there is marked Anæmia, iron may be of most service; but when the blood is poor without any apparent deficiency of red colouring matter, then are bitter Tonics needed to improve its condition, and form a valuable adjunct to the special remedies that the case may require. They ought not, as a general rule, to be administered in high fever, or when the pulse is hard, the tongue coated, or the stomach irritable. A loss of appetite, a nervous headache, a soft compressible pulse, a quivering tongue, a flabby condition of the muscles, with general inertia and indisposition to exertion, are indications for their employment. In some cases emetics and antimonials, in others mild purgatives, are of use in preparing the system for their reception.

It seems then that Debility is to be attributed generally to the state of the blood; and is to be cured by improving it. By so doing we may communicate tone to the muscular system, improve the appetite, and increase the nervous force.

Ague, or Intermittent fever, is also a blood-disease. If it were only from the analogy of other fevers, we might infer this. But there are more particular proofs. This disorder is caused by the exposure of the system to a certain peculiar poison or miasm, which is generated in the ground in certain places, and subject to known laws. The result of the influence of this miasm is a process in the blood which has been compared to fermentation, and which produces regularly recurring paroxysms of a peculiar kind. There is apparently some disturbance in the great calorifacient process, in which the blood is concerned, and not the nerves. Each fit commences with shivering; there is then a hot stage; and finally sweating. The attack then goes off, seemingly as if the poison that caused it were eliminated in the perspiration. But it is not all gone. After working in the blood for a definite period, most commonly two days, it again breaks out, and the same train of symptoms recurs. Thus this strange disorder, both in its origin and in its progress, appears to be seated in the blood. So also are its results evidenced there. Continual Ague deteriorates that fluid, causing general anæmia, and producing more or less enlargement of the spleen, which could only be brought about by some faulty condition of the circulation.

Against these proofs it has been urged that the nervous system has certainly an influence over this disorder, for that a sudden alarm has been known to arrest it. But this may occur also with other blood-diseases, and it does not prove that the nervous system is at all connected with their origin. It can hardly be supposed that Goitre or Scrofula is ever caused by a derangement of the nerves. And yet Baron Alibert relates an authentic case of a French lady who had a large goitre, which for a long time resisted all treatment, but which nevertheless disappeared entirely during the brief Reign of Terror in the French Revolution. In addition to these arguments it may be urged that Ague is often, if not always, connected with deranged hepatic functions, a fact that again points out that disease as a blood-disorder.

Seeing then that the medicines of this order of Tonics differ in each particular of their action from those remedies which influence the nerves directly, and that the diseases in which they act beneficially are essentially blood-diseases, there are sufficient grounds for concluding them to be Hæmatics, or blood-medicines.

We have now to consider the remaining minor propositions, which treat of their action as Restoratives; to ascertain whether they have been rightly allotted to this division.

Are there in healthy blood any substances which resemble them? This will appear to be a question of no small difficulty, when it is considered how little information we have actually obtained respecting the chemical composition of the vital fluid. It is nevertheless desirable that we should inquire into it to the best of our ability.

During the last few years, many propositions, intended to throw a light upon physiological science, have emanated from the fertile pen of M. Liebig of Giessen, who is rightly and universally ranked among the most illustrious of modern chemists. There are two which especially bear upon the present subject. In his first work on Organic Chemistry (p. 182,) he argued, that whereas the alkaloids Quina and Morphia resembled the brain substance in their chemical constitution, they were therefore enabled to exert a direct control over that organ by influencing its nutrition. But it is impossible to accept this explanation. The composition of the brain has been since more accurately investigated, and it has been shown to consist mainly of a mixture of albumen and fat. Now there is no reason why these substances should have a special affinity for albumen and fat in the brain, any more than for the same elements in other parts of the body. There is also no analogy at all between Quina and Morphia as medicines beyond their resemblance in chemical constitution. The theory seems to be altogether groundless.

Another, and a more important suggestion has been made by the same chemist. He has pointed out a chemical analogy between certain vegetable compounds and a substance which exists in the bile. He has shown that for the most part the elements of the bile re-enter the blood after passing into the intestine, scarcely more than the colouring matter being finally excreted with the fæces. He has found that if an enema of bile be injected into the rectum, it becomes absorbed there, and does not afterwards pass out into the urine.[33] (_Animal Chemistry_, p. 77.) What the exact function of the bile may be, is as yet undecided. Its most important constituents are, a non-saponifiable fat, Cholesterine; a neutral substance, Taurine; and an acid called Choleic, in combination with Soda,--which latter is present in excess. Bile is bitter to the taste; and ox-gall, or the bile of an ox, has been found, when administered as a medicine, to have an action which resembles that of Tonics. It appears that both the bitterness and the tonic action reside in the Taurine.

M. Liebig has pointed out an important chemical resemblance between this Taurine and the vegetable alkaloids. Of these he has singled out Caffeine, the peculiar principle of Tea and Coffee, as most analogous to the biliary product. From the analysis of these two substances he has deduced the following formulæ.

Taurine = C_{4}H_{7}NO_{10}. Caffeine = C_{8}HN_{2}O_{2}.

Then he shows that an atom of Caffeine, if added to 9 of water and 9 of oxygen, will form two atoms of Taurine. (_Organic Chemistry_, 1842, p. 180.)

It should be remarked that a different formula for Taurine has been arrived at by M. Lehmann and others, who assert that it contains Sulphur. Choleic acid, and other constituents of this complicated fluid, certainly contain sulphur. But even if Sulphur be combined with Taurine, it is not clear that it enters with it into the blood. And the above formula for Taurine has been confirmed by the analysis of M. Löwig.[34] It seems to be sufficiently correct for our purpose.

With the supposed function of Caffeine as a creator of bile, however probable or interesting, we are not now immediately concerned. We are engaged in inquiring whether there is naturally in the blood any substance which resembles the tonic alkaloids. Liebig has shown that this element of the bile is intended for re-absorption into the circulation. And without theorizing at all on the subject, it may readily be demonstrated that, with the existence in the blood of such a material as Taurine, we cannot say that we have not in that fluid an analogue to substances like Quina. Taurine is soluble in water, and crystallizable; is chemically analogous to the tonic bitter principles; and contains the same four elements as Quina. If necessary, this similarity could be exchanged for identity, and Quina could be formed into Taurine in the blood.

If there be one change in the blood to which, more than to any other, the substances which enter it are liable, it is certainly the process of oxidation. Free oxygen is continually entering the blood through the air-cells of the lungs.

The formula for Quina is C_{20}H_{12}NO_{2}. Adding to this 45 atoms of oxygen, we could make out of it one atom of Taurine, together with 16 of Carbonic acid, and 3 of water.

C_{20}H_{12}NO_{2} + 45 O = C_{4}H_{7}NO_{10} + 16 CO_{2} + 5 HO.

Thus it is conceivable that this and similar alkaloids may at the same time supply an important material to the blood, and serve as fuel to support the animal heat, by combining with oxygen and giving off Carbonic acid. I would not, of course, affirm that this actually does occur; but if it were to take place, we might gain, in this oxidation of Quina, some clue to the production of that quickening of the pulse and increase of the general temperature, which are affirmed by some to follow the ingestion of the alkaloid, even in small doses. But it is now sufficient for us if we have ascertained that there is naturally in the system, and in the blood, a substance which resembles Quina. We may be allowed to infer that the presence of the latter substance in that fluid would not be unnatural to it.

Having dismissed the second of the minor propositions which relate to Tonics as Restorative medicines, we pass on to the third. Are Quina and the vegetable bitters necessarily excreted from the blood?

It is not easy to answer this question with certainty, because it would be difficult to detect small quantities of this alkaloid in any of the secretions. But all that is known on the subject is in favour of a negative answer. A number of careful and elaborate experiments on the passage of medicines into the urine have been made by M. Wöhler, and in the long list of substances detected by him in that secretion, Quina is not mentioned. Neither has it been found in any other of the secretions. The same may be said of all the Tonic principles. There is no proof that they are necessarily excreted, but there is every reason to suppose that they may remain for a while in the blood.

Let us then consider the last question. Can Quina, or substances like it, improve the condition of the blood when deficient in any of its natural materials. We know that it is capable of curing simple debility, ague, and remittent fevers. It appears that it has also been successfully used of late by Dr. R. Dundas, in large doses, in the treatment of typhoid or continued fever. Supposing it to be proved that this agent operates in the blood, does it remedy a disease by supplying something wanting, or by counteracting something present in that fluid? In fine, is it a Restorative or a Catalytic medicine?

The probabilities which have been established, that it is not unnatural to the blood, and is not always excreted from it, are in favour _à priori_ of its being Restorative. Catalytics are generally unnatural to the blood, and are excreted because they cannot remain in it. Besides, a Catalytic has generally some peculiar action on the blood in health; but a Restorative, in moderate doses, none,--only evidencing its operation when supplying a previous want. In this also Quina and its congeners agree with Restoratives and differ from Catalytic medicines.

Arsenic is of use in Ague; and Arsenic is decidedly a Catalytic in all these particulars. In other respects, too, it differs widely from Quina. The latter is employed in debility, which depends evidently on some want in the system, and not on any morbid agent. Arsenic, on the contrary, is of use in Lepra, which, like other skin diseases, must be caused by some morbid agency, though we know not what precisely. But some diseases may be cured in two ways; either by the supply of something, or by the neutralization of something else. Perhaps Ague is one of these.

And it is not repugnant to what we know of Ague to suppose that there is in it a want of some natural material, which would have, when present, the effect of checking the operation of the morbid agent. The fact of having had Ague once does not, as in the case of the Eruptive fevers, protect a man from the disorder thenceforward. So in this sense all persons may be said to be liable to Ague, and none protected from its assault. But it is not the case with Ague as it is with Syphilis and Small Pox, which diseases most persons inevitably catch who are exposed to the virus for the first time in their lives. For, of a number of persons exposed to the same malarious influence, only a part take the disorder; some escape. It is generally found that those are most likely to take it who have been previously debilitated by any cause; so that we must suppose that the rest have in their blood some material which serves to prevent the working in it of the Ague-poison, which apparently must enter it. It is not unlikely then that Ague may be cured by supplying the want of this material.

Coupling with this consideration those facts which have been previously stated, we may reasonably conclude that Tonics are Restorative, and not Catalytic in their action; that they supply, or cause to be supplied, a material wanting in the blood. How this material is enabled to resist the morbid influence of the miasm--whether it is by an antiseptic property, such as has been attributed to Quina--I cannot determine.

Having now done my best to establish the Proposition, as applicable to Tonic medicines, I may venture to bring forward a speculation concerning their action, which I would not wish to rate higher than it is worth, and still less endeavour to demonstrate as a fact.

I have already made use of Taurine, one of the principles of the Bile, for the purpose of showing that among the natural constituents of the blood there is a substance which chemically resembles a tonic alkaloid, like Quina. This similarity admits of a further and more direct application.

It is ascertained that many, if not all, of the diseases in which Quina and its kindred medicines are found to be of use, are connected with a derangement of the secretory functions of the liver. One of these diseases is the debility which is consequent upon Typhoid and other fevers. In these fevers the function of the liver is always more or less interfered with, though more obviously in some cases than in others. In strumous habits, in which generally bark is of signal service,--and was very strongly recommended by Cullen, Fordyce, and others,--there is very commonly a peculiar degeneration of the liver, which has been ably described by Dr. G. Budd. This state is distinct from the fatty enlargement common in Phthisis, in the early stage of which disease Quinine is also very serviceable.

Quinine is often beneficial in Gout, in which the liver is always more or less deranged.

Turning to periodic diseases, we find that impaired hepatic functions are the rule, and the absence of such disorder the exception. This will be at once admitted in the case of Dysentery, and of the Remittent and Yellow fevers of the tropics. It is also true of Ague. It seems even likely that the enlarged spleen may be partly caused by an obstruction to the circulation in the liver. This affection of the spleen is not uncommon in other liver diseases.

In Typhus fever both the spleen is disorganized and the liver deranged. It is observed in tropical countries that severe forms of remittent not unfrequently pass into continued fever, which seems to point to some analogy between the two. Ague even may pass into Typhoid fever. And I have already referred to the fact that Quina has of late been strongly recommended in the treatment of continued fevers in general.

Dr. Watson states that in New Zealand the biliary functions suffer so much in the intermittent which occurs there, that it is known among the inhabitants by the name of the "Gall-fever." (_Lectures on the Practice of Medicine_, vol. i. p. 793.)

Let us now place in conjunction with these facts the similarity which has been pointed out between the bitter vegetable principles, and one of the chief constituents of the re-absorbed bile. Quina and others resemble Taurine; they tend to cure certain diseases; and these diseases depend on deranged hepatic functions. Does not this suggest the possibility that they may be of service by actually forming the Taurine, or by supplying its place in the blood? It is possible that such bodies as Quina and Cinchonia may be able to fulfil the functions of Taurine in the blood by remaining as they are, without even changing into it.

It is just possible that the presence in the blood of this bile-product, the supply of which has been cut off by the hepatic disease, might have prevented the continual action of the Ague-poison.

There is another fact which gives additional probability to such an idea. Another remedy of a different kind has been used in all the diseases in which Quina is admissible, proving in some cases superior, and in other instances second only to it in its beneficial action. This is Mercury; used in remittent and yellow fevers; of the first importance in dysentery; employed by Dr. Baillie in Ague, and pronounced by him to be in some cases superior even to Quina. In small doses it is frequently of use in cases of debility and scrofula. And Mercury is a Cholagogue; _i.e._ an agent which is known to have the effect of promoting the secretory function of the liver. Thus we may conceive that Mercury, not given in excess, or to salivation, may operate in a different way to produce the same end as Quina. One explanation would suffice for both.

If this connexion between Tonics and the Bile were actually established, then we should be enabled to explain a matter which would otherwise seem difficult to understand,--how it is that small doses of Mercury may sometimes act as Tonics, though we know that the ultimate action of this medicine, like that of other Catalytics, is to deteriorate the blood. Even in scrofulous and enfeebled cases, small doses of blue pill or of Calomel are often signally useful; and not prejudicial, as is sometimes stated by those who confound their application with that of Mercury given in salivating doses. Under such a course, when judiciously enforced, we may see the dilated pupil contract to its normal size, and the pale enervated countenance become rosy and lively; and feel the weak compressible pulse to become hard and firm. Perhaps Mercury in such a case may be indirectly tonic, by restoring to the blood the natural tonic principle of the bile.

It will be conceded that it is a great merit in a theory, when it succeeds in explaining at the same time a number of different things in a plausible way. It seems that this hypothesis of the connexion of Tonics with Taurine, or some such element of the Bile, is capable of so doing. I am very far from asserting that it is proved, or from supposing that it is at all likely to be so in the present state of our knowledge of the subject; but I think that if not evidently true, it appears at least reasonable. And it may be observed, that even should this idea be completely overthrown, which is neither impossible nor unlikely, there would still seem to be left ample evidence to prove that Quina and other vegetable bitters act on the blood on the restorative principle,--though in what exact way is uncertain.

ORD. V. CHALYBEATES.

(Protoxide, Sesquioxide, and Sesquichloride of Iron. Salts of Iron:--viz., the Carbonate; Protosulphate; Persulphate; Phosphate; Pernitrate; Peracetate; Ammonio-citrate; Potassio-tartrate. Vinum Ferri. Chalybeate Waters.)

Most of these substances are readily soluble in water. Steel wine contains a Tartrate. The insoluble oxides are doubtless dissolved by the aid of the acid of the stomach; and we find that both are most active when given in the form of hydrate, which is most easily soluble in such a menstruum. Thus Chalybeates are capable of being absorbed; and they no doubt are absorbed. They have been detected in the blood, and discovered in the secretions of urine and milk.

Being in the blood, they act by an influence which they exert upon it; for they are wanting in all the characters which distinguish nerve-medicines. They are never sudden in their action, and the effect which they produce is lasting.

Iron is found naturally in the blood; and the substance in which it is found is that which constitutes the colouring material of the red corpuscles. This is called Hæmatosin. It has been asserted by some that the red colour of Hæmatosin does not depend upon the iron which it contains. But however improbable this may be, it matters not here whether it be proved so or not; for it is sufficient that it is ascertained that Iron is essential to the chemical constitution of this red matter. Without Iron, Hæmatosin could not exist, any more than Albumen could continue to be Albumen, when deprived of nitrogen.

According to the analysis of Mulder,

Hæmatosin = C_{44}H_{22}O_{5}N_{3}Fe.

It is a very peculiar body, and apparently an essential and most important constituent of the blood; for when it is deficient, as evidenced by the paleness of the tissues in Anæmia, the whole system suffers materially, and great and general debility is produced.

The result of the administration of an Iron medicine is the restoration of this wanting colouring matter. For if the blood be analyzed before and after its employment, it is found to have undergone a remarkable change, most particularly in the quantity of Hæmatosin which it contains. A case in illustration of this is given by M. Simon, of Berlin. (_Anim. Chem._, vol. i. pp. 310, 313. _Syd. Society._) The solid constituents of the blood, in a case of Chlorosis, had increased, under the use of iron, from 128.5 to 193.5 in 1000 parts; the Globuline from 30 to 90; and the Hæmatosin from 1.48 to 4.59, in the same amount. It is probable that the increase in the Hæmatosin is the first change; that this then improves the condition of the blood corpuscles, increases their number, and through them betters the condition of the blood, and of the system generally.

In a case which came under my own observation, the blood of an anæmic girl was found, before the use of Iron, to contain only 50 parts of globules in 1000, instead of 120, the normal average. The Ammonio-citrate of Iron was prescribed, in five-grain doses, three times a day. After it had been continued for a month, the blood was again analyzed, and the amount of corpuscles found to have increased to 76 parts. After another month, they had reached to upwards of 100 in 1000 parts of blood. In the mean time the appearance of the patient had improved immensely.

Chalybeates have thus a most immediate and obvious effect in restoring to the blood this wanting Hæmatosin. As the exact chemical condition of the Iron in Hæmatosin has not been discovered, so also the precise changes which Chalybeate medicines have to undergo before they can supply this deficient material in a fit and proper form, are not known. All the known soluble compounds of Iron, except the Ferrocyanide and Ferridcyanide of Potassium, possess this Restorative power. In most Chalybeates the Iron acts the part of a base; but in some, as the Ammonio-citrate and Potassio-tartrate, it exists in a peculiar condition, and cannot be precipitated from their solutions by Ammonia. The water of Chalybeate springs generally contains a Carbonate of Iron, held in solution by an excess of Carbonic acid. The same salt is contained in the compound Iron mixture and pill of the Pharmacop[oe]ia, when these are rightly prepared.

When the Iron has entered the system, it is not necessarily excreted again from it, because it is not unnatural to the blood. To ascertain whether Iron given in small quantities is excreted by the kidneys, I have tested the urine of a patient who had been for some time taking thirty drops of the Tincture of the Sesquichloride twice a day: but I was unable to detect in it any trace of the metal.

But when given in large doses, Iron passes off by the urine and by other secretions. Some portion may be excreted by the mucous membrane of the intestines, and combine in the cavity of the bowel with Sulphuretted Hydrogen. The resulting Sulphuret communicates to the fæces a characteristic black colour. The cause of this colour was ill understood; until pointed out by Berzelius.

When the salts of Iron pass through the glands, they generally prove to be more or less astringent. The Chloride and Sulphate are most so; and they will thus be mentioned again under the head of Astringent medicines. The tincture of the Sesquichloride has obtained the reputation of being diuretic. But this constitutes no exception to the rule of its being astringent; for this diuretic power is owing to a peculiar ether, formed with the spirit by an excess of hydrochloric acid used in the preparation of the tincture.

I believe Iron to be simply and solely a Restorative remedy. By improving the condition of the blood, it appears similar in action to Tonics; but it is not a true Tonic, for neither in debility nor in Ague is it of any service, unless there is at the same time Anæmia. In some cases, even of Anæmia, Iron will not effect a cure. This must be because the appropriative power of the system is so weakened and degenerated, that it is incapable of consigning even this needful substance to its proper destination.

Anæmia is the one disease in which Iron is of use. Purgative medicines form a valuable adjunct to the treatment in most cases. Dr. G. Owen Rees has suggested that they may be of use by removing some of the water of the blood, so that the corpuscles, being then shrivelled by exosmosis of their contents, may be in a fitter condition to absorb the "ferriferous chyle." And yet, if so, the drinking of a single glass of water would probably be sufficient to swell out the corpuscles again, and thus put a stop to the process. It is just possible that a Cathartic may be serviceable by purging away from the blood some effete matters, as Sulphuretted Hydrogen, formed by the continual decomposition of the tissues, which would have hindered the operation of the Chalybeate in the blood, by decomposing it.

The use of Iron may, I think, be summed up by saying that it cures Anæmia. In this way it may benefit, and sometimes cure, other disorders, in which Anæmia is apt to be a prominent symptom. Such are Amenorrh[oe]a, Scrofula, Cancer, chronic Ague, Hysteria, Chorea, and Bright's disease of the kidney. But it seems that it can never be used advantageously in these disorders, when they are unattended with Anæmia; nor even then is it to be preferred to the other remedies specially appropriate in each case, but ought rather to be conjoined with them. Cancer, and granular kidney disease, may perhaps be alleviated, but are seldom cured. In Chorea, Arsenic or Quinine may be used, with or without Iron. Aloetic purgatives may be advantageously conjoined with Chalybeates in Amenorrh[oe]a and Hysteria. Their use may be accompanied by cold affusions, or by some antispasmodic stimulant. In Scrofula the Iodide of Iron affords us a valuable double remedy. In chronic cases of Ague, when accompanied with Anæmia, as is often the case, Iron may be prescribed with advantage.

In general Anæmia, an occasional purge, a generous diet, with good air and exercise should be combined, if possible, with the Chalybeate treatment.

ORD. VI. SOLVENTS.

(_Antilithics._

The mineral Alkalies, their Carbonates, and neutral salts with vegetable acids. Biborate and Phosphate of Soda. Benzoic and Cinnamic acids.

_Antiphosphatics._

Mineral and vegetable acids. Sour fruits.)

Of all the fluid secretions, the secretion of Urine is perhaps the only important one which cannot cease to be fluid without immediate damage to the system. The deposit of solid matter from this secretion is dangerous, because tending to the formation of a solid calculus in the kidney or the bladder, in neither case easily extracted, and acting like a foreign body in these sensitive organs. This urine, naturally clear and limpid, contains in it several substances which are by their nature insoluble, but are held in solution by certain other materials. But in some morbid states these latter materials may be wanting, or else the insoluble bodies may be secreted in such quantity that the solvent material is unable to hold them in solution. In such instances, these parts of the urine may either be separated by the kidneys from the blood in a solid state, or may be deposited from the urine after excretion or on cooling. They then fall down in a crystalline or finely divided state, and constitute Urinary Deposits.

Solvents are medicines which are employed to hold these insoluble substances in solution, where there is not enough of the natural solvent material in the system. They are medicines which tend, after being absorbed, to pass out of the blood into the urine. Although we are ill-informed as to the nature of the ordinary urinary solvents, yet it is evident that they must be present, because substances which are by their nature insoluble occur in healthy urine. And it is also evident that these medicines are able to supply their place; for, after one is given in a case of urinary deposit, this latter disappears, at the same time that the solvent remedy may be detected chemically in the urine.

In this, the last order of Restorative Hæmatics, a number of apparently dissimilar medicines are grouped together, all of which agree in this point of their action.

The deposits in which solvents are appropriate are termed respectively Lithic and Phosphatic. Among the first are comprehended Uric acid (also called Lithic,) Urate of Ammonia, and the more rarely occurring Urate of Soda. In the second set are comprised the Triple Phosphate of Ammonia and Magnesia, and the Phosphate of Lime. These deposits are each known by their peculiar form under the microscope.[35] They may easily be separated from the urine, when in any amount, and tested chemically. The Lithic deposits, (_i.e._ Uric acid and Urate of Ammonia,) are entirely dispelled by a red heat, and are soluble in alkalies. The Phosphatic deposits leave an earthy residue when heated, and are soluble in acids. When thus held in solution, the former are precipitated by an acid, the latter by an alkali, because by such a reagent that solvent is neutralized in each case.

Now the circumstances which may cause these deposits are mainly of four kinds. (1.) A wrong in the diet. (2.) An error in the normal reaction of the blood, causing these matters to be deposited, _without being themselves in excess_. (3.) The suppression of another secretion. (4.) A fault of some process of assimilation or secretion, causing _an absolute excess_ of these constituents of the urine.

Urinary sediments may be caused by slight variations in diet. Excessive indulgence in animal food or in wine may cause an over-secretion of Lithic acid. Sour drinks may cause a similar deposit, by rendering the urine acid; and sweet fruits, containing vegetable salts of the alkalies, may produce a phosphatic sediment, by rendering it alkaline. Such cases may be remedied by an attention to diet.

Again, deposits may be caused by an excess of acid or of alkali in the blood, which excess is excreted by the kidneys, and causes a lithic or phosphatic gravel, without an excess of Lithates or of Phosphates in the urine. Whatever be the condition of Uric acid in urine, it is certain that it is held in solution by some matter of an alkaline nature.[36] When this alkaline matter is neutralized by an acid, the Uric acid precipitates. This may perhaps be caused in Rheumatic fever by an excess of Lactic acid. The Phosphates are held in solution by Phosphoric acid, or by that matter which gives to healthy urine its slight acid reaction.[37] An excess of alkali in the blood, which may probably occur in Typhoid and low fevers, will cause their precipitation. Or the alkali may be formed in the bladder by the decomposition of the urine. This may occur in inflammation of the bladder; or in retention of urine caused by paraplegic paralysis.

In such cases there is no absolute excess of the deposited matter; but it is in relative excess, for the substance which should properly dissolve it is neutralized by a reagent of an opposite nature. Acids and alkalies have already been mentioned as efficacious in these instances; the former in phosphatic, the latter in lithic deposits. They directly neutralize the disturbing cause; the alkali, or the acid. They are not in such cases truly solvents; they do not themselves hold in solution the insoluble material, but they set free something else that shall be capable of doing so. (_Vide Acids; Alkalies._)

A suppression of the secretion of the skin causes a lithic deposit in some cases, as in a common "cold." For the perspiration contains a free acid, probably lactic or butyric; and when it is suppressed, the secretion of this acid is thrown upon the kidneys, and the urine is rendered more acid than naturally. The obvious indication in the treatment is to restore the function of the skin, as by warm baths, diaphoretics, etc.

It is in the case of urinary deposits produced in the fourth way that true solvents are appropriate.

From some morbid condition of the system, it happens that these insoluble constituents of the urine are secreted in absolute excess,--in a larger quantity than in health. Now the system labours to excrete them in solution, even when in excess; and often succeeds in doing so. But frequently this cannot be done, it being impossible for a sufficient quantity of the solvent material to be formed out of the blood. There is then a deposit in the urine.

We have seen that when such matters are deposited because in relative excess, the only fit mode of treatment consists in the administration of an acid or an alkali, which shall neutralize the morbid reaction of the blood. Such a case is rare; but these cases of absolute excess are much more common. There are two ways in which we may treat them; we may adopt either curative or palliative remedies. We may aim at the cause of the disease, which is generally in the blood. An absolute excess of Lithates may be caused by dyspepsia, or by a gouty disorder. This is most surely controlled by a Catalytic medicine. (_Vide Antiarthritics._) An absolute excess of Phosphates may be caused by an organic derangement of the nervous centres, when it is very difficult to cure; or it may simply be due to great nervous excitement, hard study, or melancholia. Such cases should be distinguished from a mere alkaline condition of the urine, without absolute excess of Phosphates, and may often be cured by attention to the disturbed nervous functions.

Such a curative course of treatment aims at the primary cause of the deposit; but when we are unsuccessful in our attempt to control this, or when the excess of solid matter is so great as to be positively dangerous, we are then driven to have recourse to palliative remedies. These are Solvents; medicines which pass into the blood, combine there with the peccant matters, pass out with them into the urinary secretion, and hold them there securely in solution. Such an agent may often be advantageously combined with the Catalytic remedy, which tends to cure the systemic disorder. It is a blood-medicine. Its action is so far permanent, that it effects its object definitely, dissolving and carrying away a certain portion of insoluble matter. But as it also passes out itself, it requires to be frequently repeated, because the deposit continues to be formed, and requires each time a fresh portion of solvent. It obviously acts on the Restorative principle. The deposit should be excreted in a dissolved state, but is not. The remedy therefore supplies a want.

Water is the simplest and most efficacious of all solvents, and should in all cases of gravel be very freely administered. Bouchardat has remarked that great water-drinkers are never afflicted with stone. All the urinary deposits are, to some extent, soluble in water, although _comparatively_ insoluble. Whenever the urine is of higher specific gravity than it should be in health, more water should be drunk. The average specific gravity of healthy urine is about 1.018.[38]

Acids and Alkalies are most important as solvents. They do not now act indirectly, as in the case before mentioned, but directly dissolve the insoluble matter. Acids dissolve a phosphatic, and Alkalies or their carbonates a lithic deposit, in the body, as well as out of it. Although the natural solvent may be neither an acid nor an alkali, but something else different in nature from these, yet any thing that will rightly dissolve the deposit will be fit to supply its place. Any of the free Acids may serve to dissolve a precipitated phosphate. Hydrochloric is perhaps the best of the mineral acids, although Phosphoric has been recommended on theoretical grounds. Sulphuric is the least efficacious because it does not always pass out in the urine. (_Vide Chap. IV._) Sour fruits, as Currants or green Gooseberries, may be useful in phosphatic cases; but ripe fruits have an opposite tendency. Acidulous drinks may be recommended, as Cider, Perry, and Rhenish wines. Of the free alkalies used to dissolve a lithic sediment, Potash is preferable to Soda, because it forms a more soluble compound with Uric acid. The Bicarbonates of the fixed alkalies are best, because least irritant. Bicarbonate of Soda is contained in Vichy water. The soluble Bicarbonate of Magnesia may be given with advantage. The Carbonate of Lithia has been recommended by Mr. A. Ure; but it is comparatively insoluble. The neutral vegetable salts of the alkalies, and sweet fruits which contain them, are equivalent to the Carbonates, because converted into them in the system, as has already been shown. They may be pleasantly administered in the form of effervescing draughts, in the formation of which the Carbonic acid of an alkaline carbonate is displaced by Citric or Tartaric acid.

The danger which attends the continual use of acids, or of alkalies, particularly of the latter, is that their long employment may engender a condition of an opposite nature to that which they were intended to alleviate. An acid may at length cause a lithic deposit in the urine; or, still more frequently, an alkali may produce a phosphatic sediment. Their administration should therefore be conducted with caution.

There are some other remedies which may be advantageously employed as solvents for Uric acid and Urates, whose use is not attended with this danger, and whose efficacy is a proof that the occurrence of a deposit in the urine is not a mere question of the preponderance of acid or of alkali in that secretion. The most important of these is the common Phosphate of Soda, first recommended by Liebig, who discovered that Uric acid was soluble in a solution of that salt.

If forty grains of dry Phosphate of Soda, seven grains of Uric acid, and fifteen of Hippuric acid, be dissolved in a pint of hot water, and to this solution two per cent. of Urea be added, a kind of artificial urine will be formed.

Biborate of Soda, or Borax, has also the power of dissolving Uric acid, and has been recommended in the treatment of lithic deposits by Bouchardat and Binswanger.

Mr. A. Ure has strongly recommended Benzoic acid in these cases. It passes out in the urine as Hippuric acid. (_Vide Prop. VI._) The amount of the deposit appears to decrease under the use of this remedy, but whether the formation of the Uric acid in the blood is prevented, as supposed by Mr. Ure, or whether it is not simply held in solution by means of the Hippuric acid, is not clear. Dr. Golding Bird recommends also Cinnamic acid, which is contained in Cinnamon water, and in the balsams of Peru and Tolu. It resembles Benzoic, and undergoes the same change into Hippuric acid. The salts of these acids possess a similar power.

Diuretics in general are useful in all cases of urinary deposit, for they increase the quantity of the fluid part of the urine. It is observed by Dr. Prout that healthy urine is the best solvent that we are able to supply.

When solvent remedies are employed for the purposes above mentioned, they not unfrequently fail altogether; and, as has been already observed, they require, even when successful, to be perpetually administered, or else the deposit will recur. For the solvent passes out along with each successive quantity of the Lithic or Phosphatic matter that is formed and excreted.

A radical cure of such deposits can only be effected by a medicine that shall counteract the morbid process by which they are continually produced. This cannot be done by a Restorative, but requires a Catalytic medicine. Such remedies we must presently consider. (_Vide Antiarthritics._)

Thus are concluded the six orders of restorative medicines; all of which are seen to agree together in some common characters.

When a disease depends on a want of some material in the system, then it admits of being cured by a restorative, which, in the theory of its action, is the simplest of all known medicines. And when a morbid process results in a diminution of the amount in the blood of some necessary constituent, then also may a Restorative be of use in alleviating the consequences of such a disorder; or may even effect a cure, when the morbid process has ceased, and left only its results behind it.

But when the _materies morbi_ is still working in the blood, a radical cure can only be effected by a Catalytic medicine, which shall be capable of meeting it there, and of counteracting its noxious influence.

Some Restoratives are also included among Catalytics, from a regard to a different phase of their action. The most important of these are Alkalies, which are of use in general inflammation, and also in Scrofulous and Scorbutic diseases, acting in a way that is at present but obscurely explained.

When the _modus operandi_ of a medicine is obscure, but when it is apparent that it has the power of counteracting a disease, I have preferred to place it among Catalytics, rather than to include it with Restorative medicines. But there are not many cases in which we are thus left in doubt.

The diseases curable by Catalytics are all evidently produced by an active morbid agency. Those which are treated by Restoratives are just as evidently remediable by the artificial supply or substitution of some one or more of the elements of the blood.

CATALYTICS.

These constitute the second division of Hæmatic medicines. The above name is applied to them on the assumption that their operation in the blood results in the destruction or counteraction of certain morbid agencies. ([Greek: kataluô].)

The differences in action between this and the preceding division of blood-medicines have been stated at length in the remarks on Hæmatics in general. On recurring to Prop. VII., it will be seen that it is there stated--

"That others, (medicines of the first class,) called Catalytics, act so as to counteract a morbid material or process, and must pass out of the body."

The action of the remedies in this division, which are the surest and most potent of all those that are employed in the treatment of disease, is involved in a greater degree of doubt and obscurity than that of any other class. Though there may be in some cases a certain dim explanation which we may catch hold of, and strive to fix or to render definite, yet in many instances there is not even so much as this. How can we, for example, by any of the common terms which are made use of to designate the actions of Mercury, of Arsenic, and of Iodine, express the peculiarity of their influence over Syphilis, Lepra, and Scrofula, respectively? Does it not seem better to confess our ignorance, and to say that all we know for certain is that these remedies have the power of antagonizing certain diseases?

Having done this, we may afterwards try, if we can, to invent for this action a theoretical explanation. Our arguments and theories will not affect the fact, nor will they lead us into danger, if we have first laid down the truth, however incomprehensible, as the only secure foundation, in such a manner that it shall be incapable of being disturbed by the flimsy superstructure. Some philosophers have erred in this; that they have first, with much pains and labour, erected an airy fabric on a basis of incontestable truth,--but subsequently, relying too much on that which they have themselves raised, they have commenced to pull up the blocks on which it was founded, and have thus brought the whole speculation tumbling to the ground in ruins.

Considering then that the action of Catalytic medicines in each disorder is of a special and peculiar kind, which I think will not be denied, I have grouped them in orders which are named according to the several morbid states in which they are employed.

CATALYTICA. Ord. 1. Antiphlogistica. Ord. 2. Antisyphilitica. Ord. 3. Antiscrofulosa. Ord. 4. Antiarthritica. Ord. 5. Antiscorbutica. Ord. 6. Antiperiodica. Ord. 7. Anticonvulsiva. Ord. 8. Antisquamosa.

The medicines of the first order are employed in inflammatory disorders generally, and possess an influence over the process of sthenic inflammation, however first produced. The second order contains those that are used in the several forms of Syphilis. The third, those that are employed in Scrofula. The fourth, those that are found to be useful in the cure of painful affections of the joints, as Gout and Rheumatism; and also of Oxaluria, Lithiasis, Diabetes, and other disorders of secondary assimilation. The fifth order contains those that are useful in Scurvy. The sixth, those that are employed in Ague, Remittents, and other periodic disorders, on the Catalytic principle. The seventh, those used in convulsive disorders. Lastly, the eighth, those that are capable of curing Lepra, Psoriasis vulgaris, and some other skin diseases.

The action of these medicines being much more obscure than that of Restoratives, I shall therefore have less to say about them individually, and shall not go so much into particulars. That part of Prop. VII. which refers to Catalytics, may be divided into the following minor propositions:--

_m. p._ 1.--That they act in the blood, and that their effect is permanent.

_m. p._ 2.--That each of itself tends to work out a peculiar operation in the blood.

_m. p._ 3.--That the diseases in which they are used depend on certain morbid materials or actions in the blood.

_m. p._ 4.--That the result of the action of a Catalytic medicine is in some way to neutralize or counteract some one or more of these morbid processes.

_m. p._ 5.--That these medicines are all unnatural to the blood, and must at length pass out of the system.

It might seem at first as if the first, fourth and fifth of these minor propositions would alone suffice to include the original affirmation. But a medicine may act in the blood, and may counteract a disorder; and yet it may counteract the disorder in some other way than by acting in the blood. It is necessary further to prove the disease to be a blood disease. And the evidence of counteraction will be rendered stronger if we can prove that the medicine employed is itself capable of setting up in the blood some peculiar process--of causing in it a change of some special kind. For, were it not to do so, we could hardly understand how it could meet the requirements of one case more than of another, or how it could at all arrest an active process in that fluid over which it exerted itself no particular influence. And this thing, which is laid down in the second minor proposition, can, I think, be proved in the great majority of instances.

The following is the arrangement of the subject which I have thought it best to adopt. We will, in the first place, consider some of the statements ventured by authors respecting this kind of medicines: as a comparison of these should aid us in the discovery of the truth. In the second place, it will be convenient to enumerate the medicines contained in the orders named above, and to proceed to prove the minor propositions of Catalytics taken altogether. A considerable amount of difficulty attaches to this consideration; and, as the argument which applies to one order will apply to all, much unnecessary repetition will be avoided by this plan. In the third place I must conclude by making some remarks on each of the orders in succession. To proceed now to the first of these topics.

In referring to the opinions that have been advanced on the action of this group of medicines, our task is rendered comparatively easy by the fact that a great number of writers on Materia Medica have failed to recognise them collectively. It may seem strange to one who has reflected on the subject, but it is nevertheless true, that the majority of authors have taken no notice whatever of medicines acting in the blood, with the exception of Acids and Alkalies, which are grouped by some as chemical remedies. All other medicines have been generally arranged under the two great and ill-defined heads of Nerve-medicines and Eliminatives. I cannot find it possible, by either of these terms, to give any idea of the real action of the many important agents which I have included in this division.

It would seem that it has been generally supposed that medicines,--bodies of active properties, and more or less peculiar construction,--are able to enter and to pass through a fluid which is still more complicated and changeable in nature than themselves, yet that while so doing they produce no impression upon it, but proceed passively to the solid tissues, or quietly pass out of the body, without ever leaving behind them any trace of their action.

Certain writers have made some amends by including in their arrangements a class termed Alteratives. But even then they have not unfrequently laid it down as a rule that they produce, in the first place, an impression on the nervous system, and that this has subsequently the effect of altering the manifestations of vital force. How varied and peculiar in nature must these nervous impressions be, to account for actions which are often so widely different!

The medicines thus grouped as Alteratives correspond very nearly with my division of Catalytics. The permanency of their effects, and the fact that the disorders which they cure are blood-disorders, will sufficiently stamp the character of the operation of these remedies.

In many works, as in those of Dr. Duncan, of Dr. A. T. Thomson, and more lately, of Drs. Ballard and Garrod, the existence of a class of Alteratives or blood-medicines is not even recognised or alluded to.

But in the learned classification of Dr. Pereira blood-medicines hold an important place. All except Chalybeates are grouped together in a sub-class, called Spanæmics, because they tend to impoverish the blood. In addition to those which I have named Catalytics, there are here the acids and alkalies. It is true that all these medicines, after long use, impoverish the blood, which, indeed, suffices to prove my first point, viz,: that they act in the blood, and that their effect is permanent. But Dr. Pereira has founded his classification on the physiological action of medicines, and not on their therapeutical uses, which form the basis of mine. Thus he takes no notice of the questions of what their ultimate destination may be, or what their primary _modus operandi_, whether they have to remain in the blood, or to pass out of it, and whether they can act by supplying a material to it, or by neutralizing a material in it. The subsequent statements which Dr. Pereira has chosen as the basis of his subdivisions, founded often on therapeutical action, seem in certain cases to be somewhat problematical. Thus he calls Acids "adipsa," or thirst-quenching, which very imperfectly expresses their action. Alkalies are grouped with Salts, Iodine, and Sulphur, under the general title of "resolventia seu liquefacientia," _i.e._ resolvents, or liquefacients, which involves an assumption that some might be inclined to dispute. The title of Spanæmics, applied to the whole, though unobjectionable in a classification which is founded upon their ultimate action in health, would be quite inappropriate in an arrangement like mine, which has to do with their influence in the cure of diseases. For our object in making use of such agents is not to impoverish the blood, but to obtain such a manifestation of their power as shall suffice to neutralize the noxious agent, and no more.

Dr. A. Billing (_Principles of Medicine, 5th edit._ pp. 70-75) considers that Mercury, Arsenic, Colchicum, and all the medicines which have been called Specifics, are not in fact so, but that they are capable of subduing different kinds of inflammation by causing contraction of the dilated capillary vessels. This explanation has certainly the charm of simplicity, but not, in my opinion, the merit of truth. Dr. Billing supports his argument by instancing the number of remedies that have been used in Syphilis, and considers that they must all operate in a similar way, both in this and in other disorders. Yet are all these medicines of use or advantage in Ague, in Lepra, in Chorea, and in Scrofula? But why is it not so, if all act in the same way? Their several actions should exhibit no difference in kind, but only in degree. It is the opinion of the same able authority that Mercury and Iodine diminish morbid growths by starving them; that they cut off the supply of blood by contracting the capillaries in the same way as in other cases. But why then can we not thus remove a fatty tumour, a true exostosis, or a malignant growth? We are seldom able by such means to reduce the size of a tumour, unless it depends on a blood-disorder, as Syphilis or Scrofula. The wide distinctions and the shades of difference which exist between the operations of these several medicines are surely too many and too serious to allow us to account for them all by one explanation.

But we may put aside general arguments, and appeal to facts. In the first place, it is very far from being proved that in all these disorders the capillary vessels are dilated. But let us even admit that it is so proved, and we are not then nearer to the establishment of the above hypothesis. For is the action of any medicinal agent on the capillaries constant in character?

Mr. Wharton Jones, in his Astley Cooper Prize Essay, states that he has found the effects of medicinal solutions on the capillaries in the web of a frog's foot to be very various. For even a solution of Sulphate of Copper has been known to cause dilatation, and one of Atropia to produce constriction; though the former is an astringent; and the latter a paralyzer. So that the vessels are not nearly so much under the influence of such agencies as Dr. Billing would seem to imagine. In these experiments the solutions were concentrated, and applied directly. But in the cases in point we might have two or three grains of Iodide of Potassium, one-tenth of a grain of Arsenite of Potash, or one-twentieth of a grain of Bichloride of Mercury, diluted down by about twenty pounds of blood, and extended through many miles of capillary tubes! And if simple contraction of the capillaries were required, surely Astringents, which are known to effect this, should be the most useful of all these medicines. But we do not find it to be so. Further, this idea must include a virtual denial of the causation of blood disorders by special morbid agencies.

Such are the grounds upon which is founded a denial of the existence of specific medicines--_i.e._ of remedies which are of particular or special use in one or more disorders. Is it reasonable to deny that Mercury is of particular use in Syphilis? that Iodide of Potassium exerts a special influence over secondary forms of the same malady? that Iodine and Potash are each peculiarly adapted to scrofulous cases? or that Colchicum will often stop a fit of the Gout when other medicines have failed to relieve it? If we cannot deny it, we must admit such actions to be in some degree specific. To adopt this term is to a certain extent to confess our ignorance, and for this reason many have objected to it; but this we cannot avoid. The word is, however, decidedly objectionable, when it is misapplied to express the idea of some particular medicine being the only one that can be used in a certain disorder. For this is an exaggeration of the truth that may lead to very serious error.

Before now proceeding to the proof of the minor propositions of Catalytics taken collectively, I must enumerate the chief remedies which I intend to include in the eight separate orders into which this division of blood-medicines has been divided.

_Ord. 1. Antiphlogistics._ Antimonials; Mercurials; Alkalies; Salines.

_Ord. 2. Antisyphilitics._ Mercurials; Preparations of Gold; Iodide of Potassium; Sarsaparilla (?). _Ord. 3. Antiscrofulitics._ Iodine; Bromine; Chlorine; Iodides and Bromides; Potash. _Ord. 4. Antiarthritics._ Colchicum; Nitro-hydrochloric Acid; Lemon-juice. _Ord. 5. Antiscorbutics._ Citric Acid; Lemon-juice; Fresh Vegetables; Salts of Potash (?). _Ord. 6. Antiperiodics._ Arsenious Acid; Arsenite of Potash; Alum; Chloride of Sodium. _Ord. 7. Anticonvulsives._ Preparations of Arsenic, Silver, Zinc, Lead, and Copper. _Ord. 8. Antisquamics._ Preparations of Arsenic; Sulphur; Pitch.

Under each head I have given the most important of those medicines which I conceive to act on the Catalytic principle. Other medicines may cure some of these disorders, or at least alleviate them; either by acting as Restoratives, as in the case of arthritic and of periodic disorders; or by influencing the nervous system, which plan may be effectual in some convulsive affections.

The prefix _Anti-_ involves a principle. These medicines produce certain actions which are _contrary_ to diseased actions, inasmuch as they neutralize them, and cannot subsist with them. It is granted that in some cases the actions may appear similar in some respects. But this merely shows that they move, as it were, in the same sphere, for else one of them could not meet the other. However the operation of a medicine may sometimes seem to resemble that of a disease, it is always in effect contrary to it. The similarity is of a kind which does not concern us. An acid and an alkali are so far similar, that they may both produce heat when mixed with water, and both prove corrosive and destructive to organized tissues; but they are practically contrary, and when brought together they neutralize each other. Let us now proceed to the minor propositions.

_Catalytic medicines act in the blood, and their effect is permanent._ This is simply to affirm that they belong to the class of Hæmatics, to which Restoratives also belong. Of all that I have named, there are not any, except Colchicum and Antimony, that possess in any degree the action of nerve-medicines--_i.e._ that exert a sudden and transient influence over the nervous system. I believe the sedative powers of these medicines to be quite distinct from their Catalytic influence. In the proof of the second minor proposition, I shall attempt to show that each of these remedies has a peculiar action of its own on the blood, even in health; which cannot be said of Restorative medicines. Of all these Catalytics two things are known. When they cure a disease, they do so definitely, so that it does not in general tend to return; and when they only alleviate it, the improvement effected is more or less permanent. In the second place, they are found to produce, after being long administered, a change for the worse in the blood, a diminution in the amount of Fibrine and of the red corpuscles. Thus they are blood-impoverishers, when given in excess. These considerations alone, when combined with the proof of absorption--_i.e._ that they all pass into the secretions, and may be detected there--are conclusive as to the fact of their being Hæmatic medicines. We pass on now to the third proposition, which consists in the statement of a property that is peculiar to Catalytic Hæmatics.

_Each Catalytic tends of itself to work out a peculiar operation in the blood._

This peculiar process, established by their presence in the blood, forms part of the known history of each Catalytic medicine. It will suffice to demonstrate this if I condense into as few words as possible the facts that are known on this subject, with respect to each of the orders of this division of remedies.

Of _Antiphlogistic_ medicines, some possess a power which stamps them at once as likely to be useful in the treatment of inflammatory disorders.

Alkalies are known to have the chemical property of holding Fibrine in solution. By exerting this power in the blood, it seems that they may prevent its abnormal deposition or coagulation in inflammatory cases, and at length diminish it in quantity. On this principle they were proposed and used successfully by Mascagni in acute inflammations. Their efficacy in retarding the formation of crude deposits in scrofulous and tubercular diseases may possibly be assigned to the same operation. Potash has been extolled by Dr. Theophilus Thompson as a powerful preservative for those who are predisposed to phthisical disease. Alkalies in small doses, and in cases requiring them, may be Restoratives.

Salines have been shown by Mr. Gulliver to have the effect of keeping the blood-corpuscles apart from one another. This may partly explain their action; for in inflammatory blood the corpuscles display a peculiar and abnormal tendency to aggregate together in rows. Salines also are solvents of Fibrine.

The immediate action of Mercury in checking inflammation is often very apparent in the case of Iritis. This medicine in some way diminishes the plasticity of the Fibrine of the blood; and probably promotes absorption by preventing in this way a further deposit of lymph. If the blood be analyzed after the continued use of Mercury, it is found to contain less Fibrine than in health. It has also a peculiar action of its own in the blood, for it sometimes produces various eruptions, particularly Eczema, as well as a state called Mercurial fever.

Antimony has various and marked medicinal properties: in large doses Neurotic; in all cases Eliminative. But we are now concerned merely with an agency in the blood. It has certainly some action of this kind. When rubbed on the skin it produces a pustular eruption; and M. Lepelletier gives a case in which it did this when administered only internally. Magendie found that when given to dogs it produced engorgement, and often inflammation of the lungs. Antimony seems to exert a blood-influence over inflammation somewhat similar to that of Mercury; but it further adds to this a powerful sedative effect. Antimony generally arrests inflammation by reducing the pulse; but Mercury reduces the pulse by arresting inflammation.

Thus do Antiphlogistics exert that operation in the blood which is essential to Catalytic medicines. The divisions of Hæmatics differ in this: Restoratives act by being in the blood; Catalytics by working in the blood. All we have to prove of the latter just now is to establish this part of their action.

_Antisyphilitics_ have also this action. Mention has already been made of the hæmatic effects of Mercurials. The action of the compounds of Gold is similar, though these are not now often employed. But as far back as the commencement of the eighteenth century the administration of Gold in syphilis was strongly recommended by Dr. A. Pitcairn. He employed the pure metal in a fine state of division. He also made use of a mercurial which resembled our modern blue-pill, but must have been considerably less potent, for it was given in drachm doses.

Iodide of Potassium may be said to combine the actions of Iodine and of Potash. This medicine is very active in causing the absorption of syphilitic nodes. Its use is sometimes followed by a slight cutaneous eruption.

Sarsaparilla is supposed by many to exert an alterative action in the blood; but this is not very clear, nor is its utility often very decided.

_Antiscrofulitics_ form the third order. Iodine and its compounds have certainly an action on the blood. When given in excess, or for a long time, they may cause a train of symptoms to which the collective name of _Iodism_ has been applied. The most prominent are--coryza, itching, watering of the eyes, fever, and great constitutional depression. It powerfully promotes absorption in certain cases. Its special actions will be subsequently described in the remarks made on the second and third orders of Catalytic medicines.

Potash has been already considered. Bromine and free Chlorine are very analogous to Iodine in their operation.

_Antiarthritics_ exert an influence on the blood. This is least apparent in the case of Colchicum, which is a somewhat mysterious remedy. But it has been said by some to increase the amount of Urea in the urine; by others, to promote the excretion of Uric acid. (_Vide Antiarthritics, and Chap. IV._) Nitro-hydrochloric acid contains Chlorine, which is an oxidizing agent, and probably exerts in the blood an action of this kind. It is clear that it is capable of retarding the formation in the system, and deposit in the urine, of lithic acid and oxalate of lime; though its _modus operandi_ is not determined with certainty. This question is of some theoretical importance, and will soon be considered at some length.

Among _Antiscorbutics_, Potash and its salts have been already shown to affect the blood. Their efficacy in scurvy is, however, a disputed point. That of Lemon-juice is established. It contains Citric acid and Potash; the former in great excess. Now either of these by itself would, in cases requiring it, and given in small doses, act as a Restorative. In large doses, Citric acid would disturb the reaction of the secretions, and Potash would impoverish the blood. When both together, the Citrate of Potash would undergo oxidation, and thus exert an operation in the blood of a refrigerant kind. Similar materials occur in most fresh vegetables.

_Antiperiodics_ are medicines which are used in the cure of Ague, and of other periodic diseases, on the Catalytic principle. Tonics are used in the same diseases on the Restorative plan; but their utility extends also to other cases on the same grounds. Arsenic is the most potent of Antiperiodics. The Terchloride, and the Arsenite of Potash, are the preparations most frequently employed. Arsenic produces an evident action in the blood. When given in slight excess, it is apt to bring on [oe]dema of the face, and redness of the conjunctivæ. Besides causing various nervous disorders when in large doses, its continued use may bring on a cutaneous eruption, described by Mr. Hunt as a kind of pityriasis, together with a failure of appetite, general depression, a quick small pulse, hurried respiration, and sometimes swelling of the feet. Any kind of eruption would alone constitute sufficient proof of an operation in the blood.

The metallic salts used as _Anticonvulsives_ are all capable, when taken for some time, of causing a deterioration of the blood. This is most apparent in the case of Lead, which, besides a number of nervous symptoms, tends to bring on a kind of jaundice, with general wasting of the body. Chronic poisoning by Zinc and Copper resembles that by Lead. The symptoms of what is called "Zincal intoxication" were recently described to the French Academy by M. Landouzy of Rheims, as occurring constantly among the zinc-workers. There was sometimes an [oe]dema like that produced by Arsenic.

The production of all the known nervous disorders by the presence in the blood of different metallic medicines, gives a strong additional probability to the belief that these disorders, when occurring spontaneously, are in many cases due to the presence in the blood of some unknown poison.

Among _Antisquamics_, the last Catalytic order, we meet with Arsenic again. Common Pitch is of almost equal utility in Lepra. It has some action in the blood, due to some one of its bituminous principles; but this action is not well made out, or understood. Sulphur, besides its use externally in Scabies, is administered internally with advantage both in this and some other skin diseases. It effects changes in the blood, inasmuch as it is found to combine there both with hydrogen and oxygen, and to carry them out of the system as sulphuretted hydrogen and sulphuric acid. Dr. Pereira and others ascribe to Sulphur a resolvent and liquefacient action.

Thus it is sufficiently shown that all of these medicines work out a certain process or operation in the blood, and affect the condition of that fluid. But I am very far from believing that this known operation is in all cases the one by which they neutralize morbid poisons. This action is probably of a much more inscrutable character.

Before proceeding further, I may here take the opportunity of insisting again on the differences between Catalytic and Restorative medicines. Catalytics will even in health work out their peculiar process in the blood. Restoratives exercise in that case no particular influence. The latter may remain in the blood; their office is supply or substitution. Catalytics may not remain beyond a certain time; their office is counteraction. The system then labours to excrete them. Before passing out of the body, one or two, as Colchicum, may act on the nerves. In the moment of excretion, the majority act as Eliminatives. But some, as the metals used as Anticonvulsives, are astringent, and diminish secretion generally. Mercury, Antimony, and Iodine, are among the most important Eliminatives known. They act on all glands, but on some more than on others. Antimony is also a special sedative to the Vagus nerve, and as such exerts an important influence, which enables it sometimes to cut short the process of inflammation by depressing the action of the heart.

We now arrive at the third minor proposition.

_The diseases in which these medicines are employed are active blood-diseases._

This consideration need not detain us long, for in most cases the correctness of the statement is universally admitted.

_Inflammation_ may be produced by a variety of blood-poisons, in each of which instances it partakes of a special character. Thus there are the syphilitic, scrofulous, and rheumatic inflammations. Simple inflammation may be caused by the injury of any part or organ, external or internal. It commences in the capillary vessels, and, if extensive, affects the blood generally, and produces fever. The blood then contains an excess of Fibrine, causing it, on coagulation, to exhibit the "buffy coat." There are also found in this, according to Mulder, some peculiar hyperoxides of Proteine. The colourless corpuscles are in excess; and among the red corpuscles is observed a peculiar tendency to arrange themselves together in rows. This is doubtless in some way connected with the morbid process going on in the blood.

_Syphilis_ is evidently traceable to a special poison. This is recognised by the fact of its communication from one person to another. In the system of the infected person, if left alone and uncontrolled, it breeds and increases in quantity, works out all the mischief that it is capable of effecting, and may again be propagated to others, either by inoculation into the blood, or by an equally direct transmission to a tainted offspring.

_Scrofula_ is also a blood-disease. All its manifestations are explainable on such a supposition. It is transmissible from parent to child; and it holds good as a general rule that hereditary diseases are seated in the blood. It is unaffected by any of those medicines that act only on the nerves. It produces a deterioration of the blood.

_Arthritic_ disorders are always accompanied by a change in the blood. In Diabetes grape-sugar is present there in large quantities, and has to be excreted by the kidneys. Similarly, in Oxaluria, oxalic acid is found there; in Lithiasis, lithic acid in excess. In Rheumatic fever there are profuse sweats, in which the natural acid of the perspiration is enormously increased in quantity. It is stated by Berzelius to be lactic acid. Either this, or some other acid like it, must be formed in excess in the blood. In Gout we have sometimes a deposit of urate of soda in the cellular tissue opposite the small joints. The same salt has been occasionally found in the urine in Gout. Lastly it has been detected in the blood in that disorder by Dr. Garrod, and since him, by Dr. Bence Jones. (_Animal Chemistry, p._ 29.) Thus, in all these disorders there is a wrong in the blood.

_Scorbutic_ diseases, _i.e._, Scurvy and Purpura, are characterized by a general poorness of the blood, with a special deficiency in the amount of Fibrine and of salts. There is a general tendency to hæmorrhage and ulceration all over the body. It has been observed that these diseases seldom occur in persons who are accustomed to a natural and mixed diet.

_Periodic_ disorders are known to be attributable to the entrance into the blood of a peculiar aerial poison. The mild malaria of England excites a comparatively tractable ague; that of the Maremma and of the Pontine Marshes, in Italy, brings on very fatal fevers; while the remittents that are due to the exhalations from the ground on the West coast of Africa, and in the West Indian Islands, are of a still more virulent nature. Accurate observations have shown that they are all caused by the exposure of the system to this poison, and by its working in the blood.

With _Convulsive_ disorders there is more difficulty. Although these diseases are manifested either by a derangement of the nervous system in general, or by a disturbance of the functions of the brain or spinal cord in particular, yet they are very rarely accompanied with an appreciable nervous lesion. When this is the case, as in the instance of Tetanus, which may arise from a mere irritation of the end of a nerve, they are extremely intractable, and are not at all under the influence of those blood-medicines which are useful in other cases. Epilepsy, too, may sometimes be due to a bony spicula or tumour in the brain, or to the irritation produced by intestinal worms in children; but these direct nervous causes of such convulsive disorders are to be considered as the exception, and not the rule. For they are more often connected with a diseased condition of the blood.

Epilepsy and Hysteria are frequently inherited. This supplies us with one argument. They are also apt to be brought on by various depressing causes which affect the system in general. The strumous diathesis, which originates in the fluids, and not in the nervous system, is affirmed by Dr. Cheyne and Dr. Watson to be a powerful predisposing cause of Epilepsy. Hysteria, too, is very often associated with Anæmia. Tetanus even depends very much on certain atmospheric conditions. There are sometimes, as it were, epidemics of Tetanus, in which the slightest abrasion will suffice to bring it on among the people residing in a particular neighbourhood. It is often rife in one district a long consecutive time. Facts like this must certainly be regarded as pointing to a condition of the blood as one, at least, of the causes of this terrible disorder. This condition of the blood may react upon the nerves, and maintain in them a particular morbid state. Chorea seems also to depend primarily on the state of the blood, and is indirectly curable by medicines which, like Iron and Quinine, improve its condition. In a weakly and strumous child it may be brought on by a sudden fright which would not affect one of a good constitution.

We might conclude from these facts alone that the blood is often the seat and origin of these diseases. But there is yet a stronger reason to induce us to suppose that they are frequently produced by some poison in the blood, which acts on and disturbs the nervous organs without perceptibly altering their physical construction. Many medicinal substances present us with an artificial illustration of this action. Lead, Copper, Mercury, and Arsenic, by their presence and operation in the blood, are capable of causing severe and chronic nervous disorders, particularly Paralysis and Epilepsy. Many of the vegetable Neurotics, after their passage into the blood, bring about transient nervous symptoms which are identical with those of disease. Thus Opium produces coma; Belladonna, delirium; Aconite and Hemlock, paralysis; Hydrocyanic acid, convulsions; Indian hemp, catalepsy. When the cause of these affections is removed, the symptoms disappear; when the cause returns, the symptoms return. The same is apparently the case with those unknown animal poisons that operate so as to produce nervous symptoms, without a nervous lesion.

These convulsive disorders may be treated in either or both of two ways. We may attack the supposed cause in the blood by employing one of these mineral Anticonvulsives; or we may simply apply our remedies to the nervous system, the more immediate seat of the morbid manifestations, and adopt a palliative or defensive course.

_Skin diseases_ are no doubt connected with some disorder in the blood. We might almost presume this from the analogy of the known blood-poisons, by nearly all of which an eruption may be produced. The eruptive fevers, which run a certain course, depend upon contagious poisons; but they are not under the influence of Antisquamic remedies. These are serviceable in a class of disorders, of each of which a cutaneous eruption is the most apparent, or the only obvious symptom. The true squamous disorders are Lepra vulgaris and Psoriasis vulgaris. The causes of Impetigo, Porrigo, and Scabies, are probably similar to those of the true squamæ, for they are often curable by similar remedies. The actual eruption of Porrigo is accompanied by a parasitic fungus, which may sometimes be transmitted from one person to another; and a small insect or Acarus which haunts the vesicles has been alleged as the cause of Scabies; but it is not, after all, quite clear whether these attendants may not be merely the concomitants or the results of these two disorders. At all events, Lepra and Psoriasis are true blood diseases, and are often inherited. They are more obviously under the influence of Antisquamics than the other skin diseases.

It has thus been shown that the diseases in which Catalytics are used are each to be accounted for by a process in the blood. The fourth minor proposition will not be so difficult to establish as the last, although it is in fact the most important of all.

_The action of a Catalytic results in the neutralization or counteraction of one or more of these morbid agencies._

This has already been sufficiently proved. It is established by experience that these remedies severally counteract the diseases named. They have been shown to have an action in the blood; and the diseases have been proved to be blood-diseases. Thus it is clear, that if the former counteract the latter, and have no action on the nerves, they must do it by some agency in that fluid, over the particles of which both exert an influence. They are Catalytic Hæmatics; _i.e._, medicines which, by an operation in the blood, are enabled to counteract disorders which depend upon active morbid agencies. This is all that can be positively affirmed of their mode of operation.

The fifth and last minor proposition relates to an important difference between these and Restorative medicines.--The latter may remain in the system, for if they did not do so, they could restore nothing to the blood. But Catalytics cannot restore any thing, for they are generally unnatural to the blood. They must sooner or later be excreted.

_Catalytics are unnatural to the blood, and must at length pass out of the system._

Of the list of Catalytics, the only medicines that occur as constituents of healthy blood, are Alkalies, Salts of the alkalies and earths, Chlorine, and Sulphur. Of these, the Alkalies, and possibly also the others, are not unnatural to the blood when administered in small quantities, and may remain in the system and act as Restoratives, when there is a deficiency in the blood of similar materials. But even these substances, when given in large quantity, as is the case when they are used for Catalytic purposes, are unnatural to the blood, and must be excreted from it. With respect to the other Catalytics, they cannot any of them remain naturally in the blood, under any circumstances. Their very presence for awhile constitutes an artificial disease, and is only to be tolerated or recommended because it may serve to counteract a morbid action of a more serious and uncontrollable character.

The kidneys generally constitute the channel by which these Catalytics are removed from the blood. Most of them, in passing out, act as diuretics. To this we must, perhaps, except the salts of lead, zinc, and copper. Doubtless some are excreted partially or entirely by the mucous membrane of the bowels, but this we cannot so readily appreciate. The circumstance that the astringents just mentioned are efficacious in diarrh[oe]a seems to point to their access to the intestinal surface from the blood.

It has already been shown that these Catalytics are all soluble in some way in the intestinal canal, and that they are absorbed. (_Vide Prop. I.; Prop. II._) All of them that can be detected by chemical means, have actually been discovered in the blood. But the system will not, if it can be avoided, suffer them to remain there long. The glands are charged with the office of purging the blood of all morbid materials; and thus these substances pass out in the secretions; most particularly, as I have just said, in the secretion of urine.

Every one of the medicines of this division, enumerated above,--excepting Colchicum and Pitch, which are difficult to recognise chemically,--have been detected in the urine by M. Wöhler, M. Orfila, and others. The Alkalies and Acids are combined, so as to form salts; the vegetable salts are decomposed; Sulphur has changed into Sulphuric acid; and the metallic bases are found to be variously combined; but all the fixed inorganic materials remain essentially the same, however altered in arrangement. Many of these medicines have been likewise detected in the secretions of other glands. This subject will be further discussed in the consideration of Prop. X., and does not immediately concern us now.

Thus the minor propositions may be considered as proved; and all that I have ventured to affirm of this group of medicines is, that they counteract morbid agencies by an operation in the blood.

Now the mode of counteraction is not defined, because it is only in a few cases that we can even guess at it. In the majority of instances it seems inexplicable. We know that Syphilis is a poison in the blood. Mercury also is a poison in the blood. But why does Mercury antagonize and annihilate Syphilis? The case is the same with Scrofula and Iodine; with Lepra and Arsenic. It is very humiliating to be baffled when we have got thus far; when, led by the hand of Science, we have been conducted almost to the end of this interesting inquiry, to find that we are perfectly unable to take the last step, and thus to conclude our adventure.

When there is no disease, a Catalytic medicine may work out its own action in the blood, and produce a disease. But when there is some previous disorder, the working of the Catalytic may operate so as to counteract this already existing action, being so far similar to it, that it acts in the same department, and may thus occasionally produce by an accident like results; but being, nevertheless, as we have seen, essentially contrary to it, because it neutralizes it.

Such opposite relations are met with even among natural diseases. Vaccination and Small Pox afford us an instance of the mutual counteraction of morbid processes. These poisons are alike in their operation. Dr. Fouquet, of Freiburg, has tried the effects of re-vaccination in Syphilis, on the inmates of a large military hospital, with great apparent benefit, as it is said. These poisons are unlike in their results. So are Ague and Phthisis; and persons who have had Ague are said to be less liable to Phthisis than others. Again, we find that one attack of an eruptive fever preserves the system in some way from the renewed operation of the same poison. In these morbid phenomena we find something of a parallel to the curious operation of Catalytic medicines in controlling blood-diseases; for I have shown that these remedies themselves are artificial blood-diseases.

Such ideas lead us on into the uncertain regions of speculation.

The idea that diseased actions may possibly be accounted for by supposing the existence of special _fermentations_ in the blood, is by no means a new one. Inscrutable as these diseased actions themselves may be, yet, we are enabled to recognise processes of a nature analogous to fermentation as going on in that fluid in health. Of such a kind probably are, the change of albumen into fibrine; the changes which take place in the starchy matters of the food before they can be oxidized into carbonic acid; and the changes that must occur in nitrogenous substances before absorption, as well as those that accompany afterwards the downward progress of the same materials, from living tissue into Urea and Uric acid, to be finally excreted from the system. It is a curious fact that nearly every known product of organic fermentation has been discovered in the human body in health or in disease. Lactic, butyric, and acetic acids, have been frequently found there. Dr. Heintz has lately added to these succinic acid, discovered in a hydatid cyst of the liver.

The production of many disorders by the access of a known morbid material, the working of that material on the particles of the blood after a special fashion peculiar to itself alone, and the gradual elimination of certain products, also peculiar to this one operation, are circumstances in which diseases bear an obvious analogy to processes of fermentation. The same remark applies to the working of Catalytic medicines.

It is then just possible that one of these medicines might produce in the blood a fermentation which should meet and neutralize the morbid fermentation; or that it might simply determine the latter in a different direction, and thus bring it to a desirable end. Acting in health so as to produce a morbid change, it might operate in disease by means of diverting into a right direction a change that is already going on in a wrong one.

But let us leave generalities, and descend more into particulars. Are we in a position to be able to indicate the actual nature of the changes which we thus assume to be probable?

The term Fermentation is used to express a change or series of changes of a special character, caused among the particles of a compound body, by the presence of a certain other body called a Ferment. There are two kinds of fermentation. In one the ferment itself is undergoing change, and impresses a similar change upon a substance which is analogous in nature to itself.[39] The process caused by a contagious disorder would probably be of this kind. Just as the changing yeast forms and increases itself out of the fermenting dough, so does the virus of such a disease renew and propagate itself out of the particles of the blood.

The other kind of fermentation is simpler in action, but more incomprehensible in character. It is produced by mere contact, without any change in the ferment itself. Thus it is known to chemists that spongy platinum causes the combination of oxygen and hydrogen, and exerts generally a powerful influence over the affinities of gases and liquids, without ever itself undergoing any change. The influence of Emulsine, in causing, by mere contact, the Amygdaline in the bitter almond to resolve into Prussic acid and other compounds; and that of Pepsin or of Ptyaline, in promoting the change of Starch into Sugar, is of this kind.

Considering that Catalytic medicines are not by their nature changing bodies, being mostly minerals, it is not likely that they could cause that kind of fermentation which requires that the ferment itself should be in a state of change. The influence of contact is the one which they would be most calculated to exert. I may remark that I have used the term Catalytic without any reference or allusion to this sense, in which it has been frequently employed, but merely as conveniently expressive of undoing or destroying. I would not wish, either in the terms or in the propositions which I have adopted, to assume for granted any thing which is not proved, still less an idea which is purely hypothetical.

But it is not very unlikely that some of these medicines may act in a mode which is more or less analogous to an action of fermentation of the kind just described. They might then either cause change themselves, and by this means alter and destroy a morbid process somewhat similar to that which they themselves excite; or they might, by simple contact, be able to resolve this process into a natural direction. We have seen that when introduced into healthy blood, they invariably tend to produce a change in it which is productive of harm; but that when there is already an abnormal process going on there, their influence will effect the subversion or annihilation of this other process.

And there are certain physiological considerations that render such an idea still more intelligible and plausible.

It is to be remembered that the blood, in which we suppose such actions to go on, is not an ordinary chemical fluid, subject to common laws, and influences, such as we may meet with out of the body; but a very complicated mixture, which is ever circulating and being maintained at a high temperature, and contains a number of compound organic bodies, each of which is liable to a series of varied metamorphoses.

It is not a very potent agency which is needed to disturb the chain of conditions of one of those inconstant bodies which is thus continually performing the circuit of the system.

I may briefly exemplify the series of changes, simple but momentous, which an organic body is capable of undergoing, if I instance the combination of elements which constitutes Urea.

By bringing Ammoniacal gas in contact with the vapour of Cyanic acid, we produce Cyanate of Ammonia, a poisonous salt. This, when exposed for some time to the air, changes into Urea, which is isomeric with it, but comparatively innocuous. Urea, when heated, gives off Ammonia, and becomes Cyanuric acid. On again heating this, hydrated Cyanic acid sublimes. This, when brought in contact with water, becomes Bicarbonate of Ammonia. Two equivalents of Cyanic acid, uniting in one compound, produce Fulminic acid. This, if combined with the oxide of Silver or of Mercury, forms a compound which is caused by the slightest friction to explode with terrific violence. If to the elements of this dangerous acid be added those of two equivalents of Ammonia, we again have Urea, a substance which is continually forming in the body by the oxidation of some of the nitrogenous tissues.--Urea with water changes lastly into Carbonate of Ammonia. These several compounds, alike or identical in their ultimate composition, are possessed of very different properties, whether regarded as medicinal or as chemical agents.

A similar set of changes may be produced among the elements of Uric acid, also an animal product.

Changes in some respect similar to these which are produced by the Chemist are no doubt continually going on, or capable of being set up by various influences, in the circulating blood, which is at a heat fit for such processes; in which also is a considerable quantity of free oxygen, as well as soda, ammonia, and other elements, in a state fit for combination; and to all these is superadded the agency of the vital principle, the object and effect of which is continual alteration, destruction and reproduction.

By supposing the establishment of a set of changes in the blood, we may possibly gain some insight into the cause of the powerful effects of some apparently insignificant medicines belonging to this division of Hæmatics. Neurotic medicines appear to act by their mere presence, contact and excitation. This may not always be the case with Catalytics. Their power cannot in all cases be clearly accounted for by a simple and direct influence on the blood, the muscles, the nerves, or any of the tissues. It seems sometimes as if it were on the processes that their presence sets going, and on the products thus generated, that their influence and power depend.

It may be observed that this idea of action by contact cannot by any means be supposed to favour the very unreasonable theory of the efficacy of infinitesimal doses of drugs. For such medicines must of necessity be present in some amount, or they cannot act at all. Their operation cannot be like that of the putrefying yeast, or of the poisons of contagious fevers, each of which can reproduce itself out of the elements of the changing or fermenting body. For Antimony, Mercury, and Iodine could never make themselves out of blood, which does not contain them. Like the Emulsine in the production of Hydrocyanic acid out of the material of the bitter almond, they must be present in certain quantity, or they are quite inoperative. Even a tenth of a grain would generally be powerless, not to mention such irrational quantities as the thousandth, millionth, or even decillionth of a grain. (_Vide_ page 54.) Experience--better even than theories and mathematics--is entirely opposed to such chimerical fancies.

Having thus entered into a speculation concerning the probable action in the blood of Catalytic remedies, I must once more remark that this idea forms no part of the Proposition in which I have defined their mode of operation. In the present state of our information on the subject, we cannot certainly say more than that these remedies, by some blood-action, are able to antagonize and to annihilate certain disorders in the blood.

The resolution of a disease thus effected may, in some few instances, be partly explained by certain chemical considerations, as will be particularly shown in the case of Antiarthritics.

It remains for me now to add some brief remarks on the individual _modus operandi_ of the substances included in each of the eight orders of Catalytic medicines.

Some of these having been partly discussed above, in arguing the Proposition, it will not be found necessary to travel over again that portion of the ground which has already been thus traversed.

ORD. I. ANTIPHLOGISTICS.

The inflammatory process--the chief seat of which, however it may first originate, is in the circulating blood--exerts a powerful influence over the nervous system, and may, by this influence, cause death. When fever is produced to any extent, there must be danger.

We are enabled in two ways to control or to mitigate this state of things. We may produce an action on the nervous system, or we may direct our attention to the process in the blood.

Of Neurotic medicines, which we shall have to consider hereafter, there are some which may be made use of at the commencement of the attack, and others which are appropriate when the process is more advanced. Of the first kind is Antimony, considered in its Neurotic action. Employing it in large doses, we may produce a powerful effect upon the nerves which supply the heart, and thus, by diminishing the impulse upon the inflamed parts, or on the vascular system generally, promote absorption and resolution. Blood-letting produces the same action, but in an inverse mode. Antimony diminishes the pressure on the vessels by weakening the force of the heart; Blood-letting weakens the force of the heart by diminishing the pressure on the vessels.

Such Neurotics as Opium are employed at a more advanced stage, when the inflammation cannot be suddenly put a stop to, and our object is to counteract the effects it has produced. Besides relieving the pain and nervous irritation which are so much to be dreaded, Opium may be employed to prevent a blood-medicine from passing out through the bowels. Antimony and bleeding are appropriate in sthenic cases. Opium should not generally be employed in these instances, nor should it be given in brain disorders, or in any case where there appears to be a determination of blood to the head.

Certain medicines of the class of Eliminatives, and certain Catalytic remedies belonging to the present order, are employed to counteract the inflammatory process in the blood.

Of the former, the most important are Purgatives and Diaphoretics. By diminishing the amount of the serum of the blood, they not only tend to check effusions, but act indirectly on the heart, in the same way as the medicines last spoken of; and they probably also promote the passage of morbid or of peccant materials out of the system through the glands. Acid and saline drinks may act as Diaphoretics, besides exerting each a peculiar influence in the fluids.

Of this Catalytic order, Antimony and Mercury are those which tend most powerfully to check the general blood-process of inflammation. The former is used in urgent and acute cases to make a sudden and powerful impression, adding to its Hæmatic action a sedative effect on the heart and circulation. Mercury exerts no such immediate influence. Diminishing the Fibrine of the blood, and having other operations of a peculiar kind in this fluid, it powerfully promotes absorption and counteracts effusion, in all inflammations. The blood-action of these remedies, though not positively slow, is slow when compared to an action on nerve. Thus when Antimony is given in large doses, as is desirable in some highly sthenic and dangerous attacks, its blood-action is lost in its immediate Neurotic operation.

So that in Croup and Pneumonia, both rapid and fatal inflammations, Antimony is far preferable to Mercury. But in Pleurisy--where there is generally no immediate danger to be dreaded, but a subsequent effusion, Mercury is best, being in time to lessen or to prevent this result.

From the action of both on the blood, and one on the nerves, these are very lowering remedies. In the employment of Antimony in fevers and inflammations, the production of nausea generally indicates that it has taken sufficient effect; but it may sometimes be better to give such a dose as shall cause vomiting, especially when a violent counter-irritant action is to be desired. The increase in the quantity of saliva, and slight soreness of the mouth, which result from its action, will show when the administration of a Mercurial has gone far enough. It is seldom advisable to cause copious salivation.

Alkalies dissolve the Fibrine of the blood, and appear by this to lessen its deposition, and retard its formation. Thus, when given in large doses, they operate as Antiphlogistics. They have sometimes been employed with advantage in fevers of the acute or sthenic kind. Exerting an influence over the inflammatory process considered _per se_, Alkalies and Mercurials are more particularly efficacious in some special varieties of inflammation, because in such cases they further counteract the morbid agency by which the process is excited and kept up.

In the Typhoid and Eruptive Fevers, when the blood is already sufficiently deteriorated, and it is not desirable that we should reduce the vital powers beyond a certain point, Salines, as Nitrate and Chlorate of Potash, supply us with a set of valuable and sufficiently mild Antiphlogistic agents. It seems that they both exercise a solvent power over Fibrine, and keep asunder the corpuscles which tend to adhere together in inflammatory blood. This latter action has been observed by Mr. Gulliver. Salts are excreted, and act on the skin, or the kidneys, or the bowels. They are not so potent as Alkalies; for salts pass out of the body as they went in; but Alkalies pass out into the secretions as salts, having first combined with acid in the system, so that they must leave behind them a certain excess of alkali in the blood, by which their action is continued for some time. (_Vide Alkalies; Prop. VIII.; Antimony and Mercury in Chap. IV._)

ORD. II. ANTISYPHILITICS.

These are medicines whose operation in the blood results in the counteraction or neutralization of the syphilitic poison.

In primary forms of Syphilis, as the chancre, and early eruptions,--as syphilitic Lichen, Roseola and Lepra,--also in syphilitic Iritis, Mercury is the single and best remedy.

Its power is universally admitted, both by English and Continental surgeons. It is often esteemed a specific. Among others, Mr. Hunt, in a treatise on Syphilitic eruptions, maintains that Syphilis has a tendency to go on without limit if left alone, but that Mercury in sufficient doses possesses the power of totally destroying the poison, and preventing its transmission.

Mr. Carmichael was of opinion that Mercury was only applicable in those cases which exhibited the true Hunterian chancre, round, cup-like, and hard, followed by a leprous eruption. But it is more in accordance with common experience to say that the only contra-indications to the use of Mercury in primary Syphilis are these--a scrofulous or very debilitated state of the system; and a sloughing or irregular appearance of the primary sore.

We may administer Mercury in two forms. It may be given as Calomel or Blue pill, with or without Opium, and continued until it affects the mouth. Or the Bichloride may be administered in minute doses, and may prove efficacious without producing salivation. It should be commenced as early as possible; and in most cases the action of Mercury in the blood, of whatever nature that action may be, will meet and neutralize the advance of the syphilitic virus, preventing its further manifestation in a secondary form. It is rarely necessary to push its action beyond the first symptom of salivation; for that will be evidence that the system is sufficiently saturated with it. Beneficial as it often proves when administered thus cautiously, yet, if given in excess, or to individuals that are over-susceptible of its action, it is capable of proving a poison every whit as noxious as the Syphilis which it was intended to neutralize. The mercurial cachexy is quite as deplorable, and quite as incurable as the Syphilitic cachexy.

The Terchloride of Gold may be used in Syphilis in the same way as the Bichloride of Mercury; but it is much more seldom employed. There seems to be a strong medicinal as well as chemical similarity between these two metals and their compounds. Even the insoluble metal itself was used some time ago as an Antisyphilitic, apparently with success. In 1715, Dr. A. Pitcairn recommended finely-powered Gold as even more efficacious than Mercury in the treatment of Syphilis.

In secondary forms of this disorder, as in Periostitis, ulceration of the mouth and throat,--or in any of the late rashes, as Rupia,--Iodide of Potassium is the best remedy. Its efficacy in such cases was discovered by the late Dr. Williams. It may sometimes fail to effect a cure; but this failure is often due to the omission of Mercury in the treatment of the primary disease. It would seem as if it were not so much the real secondary syphilis, but a certain smouldering action of a part of the poison which has escaped the operation of Mercury, but has been modified by it, which is capable of being met and controlled by Iodide of Potassium. In cases where this remedy fails, I have found that a course of the Bichloride of Mercury, combined with Sarsaparilla or some bitter tonic, proves very beneficial.

But the action of the Iodide on a case of Periostitis, and the rapid absorption that follows its exhibition, are sometimes fully as remarkable as the influence of Mercury over the primary disorder.

Sarsaparilla is a very doubtful member of this order. It contains a soluble principle called Smilacine. It is thought by some to purify the blood, and also to have a kind of specific influence over it in old syphilitic cases. If it were so, we should have from the vegetable kingdom a distinct analogue to one of these mysterious mineral Catalytics. But it is so rarely given without being combined with some more powerful agent, that it is difficult to judge whether or not it may have any striking virtues of its own.

The Antisyphilitics, particularly the insoluble compounds of Mercury, are frequently employed as local applications to sores and eruptions. When these have a syphilitic origin, the mercurial doubtless combats the local manifestation in the same way that it can counteract the general action in the blood. In other cases the Mercury may pass into the blood of the part, and, by exerting in its antiphlogistic operation, the result of which is to diminish its plasticity, may thus promote absorption. Mercurial ointment, if rubbed into the skin, becomes in part absorbed, and may thus produce salivation.

ORD. III. ANTISCROFULICS.

These are medicines which have the power of counteracting the poison of Scrofula in the blood. Common and pernicious as is this disease, there are not many Catalytic remedies which exert any marked control over it. When a strumous condition is chronic, and has firmly established itself--when it has descended through many generations of the same family,--it is very intractable and difficult to cure. Palliative and indirect remedies, aimed rather at the consequences than at the source of the disorder, are often adopted with benefit. Tonics, Chalybeates, Cod-liver oil, and cold bathing, are frequently of use in improving the condition of the system, when debilitated by the long continuance of strumous disorders. But the most important and direct remedies for Scrofula are to be found in Iodine and its compounds.

It is not to be wondered at that in many cases of deeply-rooted blood-disease, complicated perhaps with anæmia, structural change of organs, disordered assimilation, and various nervous symptoms, all remedies alike should prove useless. So that the experience of many practitioners, thus frequently disappointed in their hopes of a cure, has led them to question altogether the efficacy of Iodine in Scrofulous disorders. But it is generally allowed that it is more beneficial in such cases than any other medicine, and is the only remedy which is universally applicable in Scrofula. If this be true, it follows that it must have a special power over this blood-disease.

Burnt sponge, and the ashes of a seaweed, the Fucus vesiculosus, both of which contain Iodine, have been used in Scrofula from very early times. But it was not until the present century that Iodine was discovered, and its efficacy in Scrofula, particularly in the cure of Goitre, pointed out by Dr. Coindet of Geneva. After this it came to be generally applied in all Scrofulous cases, and was especially recommended by M. Lugol in France, as a specific for such maladies.

When given for some time, Iodine has the effect of impoverishing the blood, like Mercury and many other Catalytics, diminishing in it the amount of Fibrine. All remedies which do this favour absorption. This effect is obviously connected with the alteration in the blood, and there is no reason to suppose that any special stimulant action is exerted on the absorbent vessels. Those Catalytics which favour absorption are not all useful in the same cases, but some are most useful in one disorder, some in another. Thus they must exert a special action over morbid poisons; an action which is altogether distinct from the influence over absorption, although by this latter they may be able to cause the disappearance of effused products, and of tumours produced in various ways.

In some rare cases Iodine has even been known to cause the absorption of healthy glands, as the mammæ and testicles.

Iodine and Iodide of Potassium, when successful, do not merely cause the disappearance of scrofulous tumours, but further meet and neutralize the poison which is working in the system, and effect a more or less permanent cure. This could hardly be done by a remedy which had only the power of promoting absorption.

It seems that some systems are able to bear with impunity very large doses of Iodide of Potassium. I once met with a medical man who denied its power altogether, because he himself had frequently taken a scruple, and sometimes a drachm at a time, without any effect. Other men are readily affected by very small quantities, and quickly experience the symptoms of Iodism. It is probable that in the former case the medicine is very quickly eliminated by the kidneys; but that in the latter it remains in the system for some time.

The Iodide of Iron is a most useful medicine for scrofulous children, who commonly suffer under Anæmia, as it combines a Chalybeate with an Antiscrofulic action.

Bromine and Chlorine resemble Iodine in their Antiscrofulic effects. It is said that Scrofula and Consumption are unknown among the workmen in bleaching factories, where Chlorine is being constantly inhaled. Thus it has been strongly recommended that diluted Chlorine should be constantly inhaled by consumptive patients. It is probable that part of the efficacy of sea-side air and sea-voyages in scrofulous cases may be due to the free Chlorine which is given off in small quantities from the salt water of the ocean. The powers of Iodine and Bromine are shared by their compounds; and probably Chlorine is no exception to this rule. The bad consequences which follow the omission of common salt from the food, are sufficient to show that this substance has a beneficial action on the blood. Probably large doses of this article of diet would be found advantageous in Scrofulous disorders.

It is easy to recognise such an action as that of Iodine in Scrofula, but it is almost impossible to invent a satisfactory explanation for it.

Potash, free or carbonated, is another remedy of considerable importance in Scrofulous diseases. It is possibly one of those Catalytics which exert a simple chemical influence. It may act by holding in solution fibrinous and fatty matters, and preventing their abnormal deposit in a crude form in the shape of tubercular matter. It may also be found useful in cases of Syphilis, when aggravated by a previously existing strumous tendency, and where a course of Mercury cannot be safely prescribed.

Small doses of Mercury, as an alterative, are often efficacious in scrofulous constitutions. They appear to act simply by stimulating the torpid liver to a performance of its proper function.[40] (_Vide_ page 144.)

Potash has been used as a prophylactic against Consumption. The efficacy of Cod Oil in this disease has been explained by some as depending on the Iodine which it contains in small quantities. I do not consider this explanation to be the correct one. (_Vide Cod Oil, in Chap. IV._)

ORD. IV. ANTIARTHRITICS.

In this order are included some blood-medicines which exert a direct influence over certain disorders which depend on some fault in the complicated processes of assimilation and nutrition. The chief of these diseases are, Diabetes; Oxaluria; Lithic deposit in the urine; and the true Arthritic disorders, _i.e._, Gout and Rheumatism. Most of those blood diseases which cannot be clearly traced to the introduction of a poison from without may be arranged under this head, and appear to be curable by the same set of remedial agents.

There are certain processes always going on in the blood, whose continuance in the right direction is essential to health. When one of these processes is disturbed, it does not generally cease, but it goes on then in a wrong direction.

The natural processes result, on the one hand, in the preparation of fit and proper nutriment out of the materials of the digested food, for the growth and support of the several tissues and functions; and, on the other hand, in the gradual change and conduction out of the body of the products of the waste of those tissues. But when any process goes on in a wrong direction, it results in the formation of various products different from those which are required, and which the kidneys and other glands are at length called upon to excrete from the system. The result is that the general health is more or less seriously impaired.

There is also another way in which these diseases are not unfrequently caused. A natural process may stop at a certain point, and go no further. The material formed at that stage remains as it is. It is not wanted; it is morbid; and it also is excreted from the body. It is possible that these errors in the assimilative processes may sometimes arise in the first instance from a deficiency in the blood of some substance whose influence was necessary to the proper conduct or control of the natural series of changes. Some of these conducting materials may be formed by the liver; for it is found that these disorders are very commonly connected with an impairment of the function of that organ. Thus Mercury, which restores the secretion of the liver, is often useful in Arthritic disorders; as also is Quinine, which has already been shown to have a peculiar relation to liver diseases.

But these disorders, however they may first originate, consist in an active morbid process of one kind or another; and the surest way of counteracting this process, or of diverting it into a right direction, is by the employment of one of the Catalytic medicines contained in this order. Some stages of these diseases are attended with a want in the blood of some of its ordinary constituents; which condition may be relieved by the supply of a Restorative remedy.

Thus in this group of disorders three kinds of medicines may be employed, which tend in various ways to improve the condition of the blood.

Acids and Alkalies are sometimes needed, and act on the Restorative principle. The true Antiarthritics are those medicines which are employed on the Catalytic plan, to meet and neutralize the morbid material or process in the blood. And sometimes Eliminatives are made use of, which seem, by acting on the secretions of the skin, kidneys, or bowels, to be able to rid the blood of an unnatural product. Thus Guaiacum and Salines are employed in Rheumatism, and Purgatives in Gout.

These two joint affections are most characteristically under the influence of Catalytic remedies. Diabetes and Lithiasis are more under the control of Restoratives than the others.

The medicines composing this fourth order of Catalytics have been already enumerated.

That Colchicum tends in some way to neutralize in the blood the poison of Gout, and to a less degree that of Rheumatism also, is generally admitted, although various theories have been adopted to explain this action. (_Vide Chap. IV. Art. Colchicum._)

In Oxaluria, the employment of Nitric acid as a remedy was first recommended by Dr. Prout. Dr. Golding Bird advised the substitution of Nitro-hydrochloric acid, which has proved to be a most valuable remedy, not only in this disorder, but also in some cases of lithic deposit. The Oxalate of Lime rarely occurs alone in the urine; there is generally along with it some Urate of Ammonia. The causes of the two deposits appear to be in some way connected. So also are the remedies similar. Dr. G. Bird has found Colchicum to be of signal service in cases of lithic deposit in the urine; and has proved the same medicine to be efficacious in Oxaluria.

I will now attempt to show how the action of these medicines may admit, on certain grounds, of a chemical explanation. There are very few Catalytic actions in which such an explanation can be attempted, but a degree of plausibility appears to attach to the idea in this case, though it cannot of course be considered to be susceptible of more than a demonstration of probability.

I have already said that in all the disorders now under consideration there are certain morbid constituents in the blood which have been recognised by chemical tests. In Diabetes there is an excess of grape-sugar formed in the blood, and excreted from it in the urine. In Rheumatism we have a painful joint affection, attended with a great development of acid in the system; and this acid, which we have many reasons for supposing to be lactic acid, is occasionally excreted by the skin. In Gout we meet with another Arthritic affection, in which there is urate of soda in the blood, and an excess of uric acid and urea in the urine. A simple excess of uric acid in this secretion constitutes Lithiasis. There is an obvious but ill-understood connexion between the last two disorders, and, indeed, between all those of which we are treating. In Oxaluria we have an abnormal formation of oxalic acid in the blood, which is excreted in combination with lime, for which base it has a great affinity. In oxalic urine there is generally an excess of urea, as I have found in many cases.

Now it seems to me that all these disorders are capable of being explained by reference to the series of changes in the blood which are associated with the respiratory process. (_Vide Liebig's Anim. Chem._,